Optical device module and method of manufacture

Abstract: An optical device module comprises a module body including an optical device, a first fiber connector holding a first optical fiber, coupled to one end of the optical device, and a second fiber connector holding a second optical fiber, coupled to the other end of the optical device; and an enclosure body integrally molded with a resin such as an epoxy resin, an urethan resin to coat the module body. Almost whole module body is coated with the integrally molded epoxy resin, so that the module body is protected efficiently from the external heat, moisture, mechanical shock etc.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an optical device module to be utilized in optical fiber communication networks and others, and to a method of manufacturing the optical device module. Related Background Art An optical device module comprises an optical device which is generally a waveguide substrate with an optical waveguide formed on a surface thereof, and fiber connectors coupled at both ends of the waveguide substrate, which are arranged so that each optical fiber supported with the fiber connector is optically coupled with the corresponding optical waveguide on the waveguide substrate. Here, the optical devices include a waveguide substrate itself, a waveguide substrate with various kinds of optical components, and a waveguide substrate the waveguide forming surface of which is covered with a resin or others. In the optical device module, if the coupled portion between the waveguide substrate and the fiber connector is exposed to the ambient atmosphere, the adhesive strength of the adhesive in the coupled portion is degraded due to heat, moisture etc., which increases the light loss and light reflection in an optical coupled portion. Moreover, if the coupled portion is exposed, the optical device module is weak against the mechanical shock. As a countermeasure, conventionally, the waveguide substrate and the fiber connectors are stored in a housing, and a jelly-like resin is filled in the housing as a cushioning material. Such techniques disclosed in Japanese Patent Laid-Open No. HEI 5-27139 (27139/1993), Japanese Patent Laid-Open No. HEI 5-45531 (45531/1993) etc. are known. However, in the above-described conventional technique, because the housing is a two-piece housing assembled with two identical half bodies, there is a possibility that the sealing between the half bodies may be failed. As a result, the module may be influenced by the external heat, moisture etc. Further, in the case of the two-piece housing, it is hard to fill the jelly-like resin into the housing without any space left. SUMMARY OF THE INVENTION Thus, the object of the present invention is to provide an optical device module which is capable of protecting a module body efficiently from the mechanical shock, heat, moisture etc. and a method for manufacturing such an optical device module. To achieve the aforesaid object, the invention provides an optical device module as defined in claim 1. In this optical device module, it is preferable that the second resin in the form of a gel interposed between the enclosure body and the module body is a resin such as a silicon resin or urethan resin. A method of manufacturing the optical device module with the above-described configuration is defined in claim 9. To interpose the second resin between the enclosure body and the module body, before the module body is placed in the mold, the second resin in the form of a gel is applied onto the whole module body. In the optical device module with the above-described configuration, almost the whole module body is coated with the integrally molded first resin, so that the module body is protected efficiently from the external heat, moisture, mechanical shock etc. Especially, as the second resin in the form of a gel is interposed between the enclosure body and the module body, the gel resin functions as a cushioning material and accepts the movement of the fiber connectors due to the thermal expansion or thermal shrinkage of the adhesives between the fiber connectors and the optical device. The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWING Fig. 1 is a sectional view showing an optical device module according to the first embodiment of the present invention. Fig. 2 is a view showing a manufacturing process of the optical device module in Fig. 1, which is an exploded perspective view of a module body. Fig. 3 is a view showing a manufacturing process of the optical device module in Fig. 1, which is a perspective view showing a completed module body. Fig. 4 is a view showing a manufacturing process of the optical device module in Fig. 1, which shows the module body being suspended like a bridge. Fig. 5 is a view showing a manufacturing process of the optical device module in Fig. 1, which shows the module body being placed in a mold of a molding device. Fig. 6 is a sectional view showing an optical device module according to the second embodiment of the present invention. Fig. 7 is a sectional view showing an optical device module according to an embodiment not covered by the present invention. Fig. 8 is a sectional view showing an optical device module according to the third embodiment of the present invention. Fig. 9 is a view showing a manufacturing process of the optical device module in Fig. 8, which shows a module body being supported with a support rod in a mold of a molding device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described in detail with reference to the drawings hereinbelow. In the following description, like references characters designate like or corresponding parts throughout the several views. Fig. 1 is a sectional view of an optical device module 100 of the first embodiment. Figs. 2 to 5 show a manufacturing process of the optical device module 100 in Fig. 1. As the process is being described, the configuration of the optical device module will be apparent. In the drawings, the reference numeral 10 designates a waveguide substrate which is an optical device in the optical device module 100 and in which a 1x4-branch optical waveguide 12 is formed on the surface thereof. In general, such a waveguide substrate 10 is formed using a method for depositing fine particles of SiO 2 on a surface of a silicon substrate by frame hydrolysis (FHD: flame hydrolysis deposition method). To end faces of the waveguide substrate 10 where the end faces of the optical waveguide 12 are located respectively, a first fiber connector 14 for holding one end of a first optical fiber 16 and a second fiber connector 18 for holding one end of a second optical fiber 20 are adhered respectively. The first optical fiber 16 comprises a bare fiber 16a, a primary coating (not shown), e.g. of a silicon resin, coated on the bare fiber 16a, and a secondary coating 16b, e.g. of a nylon, coated on the primary coating. As clearly shown in Fig. 2, the first fiber connector 14 comprises a V-shaped-groove substrate 22 with one V-shaped groove 24 formed on the surface thereof, and a holding plate 26 to be adhered on the surface of the V-shaped-groove substrate 22. One end of the optical fiber 16 with the exposed bare fiber 16a is set in the V-shaped groove 24 of the V-shaped-groove substrate 22. Then, the holding plate 26 is adhered on the V-shaped-groove substrate 22 with an adhesive 28, by which the optical fiber 16 is held with the optical fiber connector 14. The second optical fiber 20 is called a tape fiber optic cable or a ribbon fiber optic cable. The optical fiber 20 has a plurality of primarily coated bare fibers 20a (four in this embodiment) which are arranged parallel to one another and secondarily coated, e.g., by the nylon 20b to be bundled flatly. The second fiber connector 18, as similar to the first fiber connector 14, comprises a V-shaped-groove substrate 30 and a holding plate 32. There are four V-shaped grooves 34 parallel to one another formed on the surface of the V-shaped-groove substrate 30. The ends of the exposed bare fibers 20a of the optical fiber 20 are set in the respective V-shaped groove 34. Then, the holding plate 32 is adhered on the V-shaped-groove substrate 30 with an adhesive 36, by which the second optical fiber 20 is held with the second fiber connector 18. It should be noted that as shown in Fig. 2 and Fig. 3, before the fiber connectors 14, 18 are coupled to the optical fibers 16, 20, it is preferable that rubber protecting boots 38, 40 which are fitted on the completed product are put on the optical fibers 16, 20 beforehand, respectively. Further, the V-shaped-groove substrates 22, 30 may be formed, e.g., by grinding or etching a silicon substrate. Next, as shown in Fig. 3, the first and second fiber connectors 14, 18 are adhered on the respective end face of the waveguide substrate 10 with an adhesive, preferably an ultra violet ray curing adhesive 42. At this point, the first and second fiber connectors 14, 18 are positioned in respect to the waveguide substrate 10 so that the end face of each bare fiber 16a, 20a of the optical fiber 16, 20 is optically coupled with the respective end face of the optical waveguide 12. After a module body 44 comprising the waveguide substrate 10 and the fiber connectors 14, 18 is formed in the above-described manner, as shown in Fig. 4, the proper portions of the first and second optical fibers 16, 20 are clamped by support devices or clamps 46, 48, respectively. Then, one or both of the clamps 46, 48 are moved so that one clamp 46 or 48 is apart from the other clamp 48 or 46. Consequently, a certain tensile force acts on the optical fibers 16, 20, and the module body 44 is suspended between the clamp members 46, 48, like a bridge. Thereafter, a gel-like or jelly-like resin 50 having a proper viscosity is applied onto the whole module body 44 without any space left. The resin 50 must have the fluidity so that the resin can be applied on the module body 44 and must have the proper stickiness or adhesion after the application so that the resin is not dropped from the module body 44. Moreover, the resin 50 preferably has the heat resistance and the moisture resistance. As this sort of the resin 50, a silicon resin (e.g., trade name: Silicone Gel product of Sin-Etsu Corp.) or an urethan resin (e.g., trade name: PEL-URETHANE product of Nippon Pelnox Corp.) can be used. Next, as shown in Fig. 5, the module body 44 on which the resin 50 is applied is placed in a mold 52 of a molding device while being suspended between the clamps 46, 48. At this point, the module body 44 is placed substantially in the center of the space of the mold 52 and spaced apart from the inner wall surface of the mold 52. Thereafter, a proper resin 54 is injected into the mold 52 and cured. The resin 54 must form a certain shape after cured, and must have the heat resistance and the moisture resistance. As this sort of the resin 54, a thermosetting epoxy resin (e.g., trade name: EPOTECH product of Epoxy Technology Corp.) is preferable. When this thermosetting epoxy resin is used, it is effective that the module is molded in accordance with the transfer molding. Alternatively, an ultra violet ray curing resin (e.g., trade name: OPTO-DAINE product of DAIKIN Corp.), a silicon resin (e.g., trade name:Silicone Gel product of Sin-Etsu Corp.), an urethan resin (e.g., trade name: PEL-URETHANE product of Nippon Pelnox Corp.) etc. can be used. After the resin 54 is cured, the mold 52 is removed and the clamp members 46, 48 are removed from the optical fibers 16, 20. There are boot attaching portions 56, 58 (Fig. 1) to which the aforesaid protecting boots 38, 40 are attached and which are formed at both ends of the cured resin 54, that is, an enclosure body 54. When the protecting boots 38, 40 are fitted on the boot attaching portions 56, 58, the optical device module 100 shown in Fig. 1 is completed. In the optical device module 100 formed in this manner, the enclosure body 54 surrounding the module body 44 is molded with the epoxy resin or the like, so that the shape of the outer appearance is constant. Moreover, since the module body 44 is surrounded by the molded resin 54, the module body 44 is completely sealed from the external environment. Therefore, the module body 44 is protected efficiently from the external heat, moisture, mechanical shock etc. Further, since the gel-like resin 50 is interposed between the module body 44 and the enclosure body 54, the module body 44 is protected from the external environment by the resin 50. The module body 44 is immersed in the gel-like resin 50, and then floated and supported inside the enclosure body 54. Since the resin 50 has the proper viscosity, if the mechanical shock is applied to the optical device module 100 from the outside, the shock is absorbed by the gel-like resin 50. Therefore, the gel-like resin 50 functions as the cushioning material. Moreover, even though the heat is applied to the optical device module 100 and the adhesive 42 in the coupled portion of the module body 44 is thermally expanded or thermally shrunk, the gel-like resin 50 can accommodate the movement of the fiber connectors 14, 18. There is shown in Fig. 6 an optical device module 200 formed in accordance with the second embodiment of the present invention. The optical device module 200 of the second embodiment is different from the optical device module of the first embodiment in that the gel-like resin 50 is not applied onto the whole module body 44. In this case, the gel-like resin 50 is applied onto the whole first and second fiber connectors and portions of the waveguide substrate 10 adjacent to these fiber connectors 14, 18. Since to be influenced by the external mechanical shock, heat and moisture is the coupled portions between the fiber connectors 14, 18 and the waveguide substrate 10, and the fiber connectors 14, 18, if at least these parts are protected by the gel-like resin 50, the same effect as in the first embodiment will be attained. When the urethan resin is used as the gel-like resin 50, it can be used in the form of a gel. But, because the cured urethan resin is superior in elasticity, it can be used as a cushioning material. For this reason, like an optical device module 300 shown in Fig. 7 not covered by the present invention, an enclosure body 60 made of urethan resin is directly formed around the module body 44. Fig. 8 shows an optical device module 400 formed in accordance with the third embodiment of the present invention. In the case of forming the optical device module 100 of the first embodiment, the module body 44 is supported and suspended by the clamps 44, 46. However, in the case of the optical device module 400 of the third embodiment, without using the clamps, the bottom surface of the waveguide substrate 10 in the module body 44 is supported by at least one support rod. In detail, after the first and second fiber connectors 14, 18 are coupled to the waveguide substrate 10, the gel-like resin 50 is applied onto the module body 44 except the center portion of the bottom surface of the waveguide substrate 10. Thereafter, as shown in Fig. 9, the center portion of the waveguide substrate 10 rests on an upper end face of a support rod 62 projecting from the bottom surface of mold 52 of the molding device. Then, the melting resin 54 such as the epoxy resin is injected into the mold 52 and cured. Formed in this manner is the optical device module 400 shown in Fig. 8. In Fig. 8, a hole denoted by the numeral 64 is formed when the support rod 62 is removed. This hole 64 can be utilized in the various measurement, for example, the measurement of internal temperature of the optical device module 400. It should be noted that since a portion 66 of the enclosure body 54 surrounding the upper end of the hole 64 is tightly in contact with the bottom surface of the waveguide substrate 10, water and others do not enter through the hole 64 and never reach the fiber connectors 14, 18. The preferred embodiments of the present invention have been described in detail but it is needless to say that the present invention is not limited to the above embodiments. For example, the resin composing the enclosure body of the optical device module and the gel-like resin are not limited to the above-described ones but any suitable resins can be used. Further, the optical device may be the one that an optical component is placed onto the optical waveguide forming surface of the waveguide substrate. As described above, according to the present invention, almost whole module body is coated with the integrally molded resin such as epoxy resin, so that the module body is protected efficiently from the external heat, moisture, mechanical shock etc. Even though the adhesives between the fiber connectors and the optical device are thermally expanded or thermally shrunk, the gel-like resin accepts the movement of the fiber connectors. Therefore, the excess force does not act on the module body. According to the method of the present invention, after the gel-like resin is applied onto the module body, the enclosure body is formed, e.g., in accordance with the transfer molding method. Therefore, the module body is resiliently immersed in the gel-like resin without any space left. From the invention thus described, it will be obvious that the invention may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention as defined in the claims, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims: An optical device module (100, 200, 400) comprising: a module body (44) including an optical device (10) having first and second ends, a first fiber connector (14) holding a first optical fiber (16) coupled to the first end of said optical device, and a second fiber connector (18) holding a second optical fiber (20), coupled to the second end of said optical device; and an enclosure body (54) of a first resin and integrally molded so as to enclose the whole of said module body (44); characterized by a second resin (50) in the form of a gel interposed between said enclosure body (54) and said module body (44). An optical device module according to Claim 1, wherein said second resin (50) is located at least on the peripheries of said first and second fiber connectors (14, 18) and the peripheries of coupled portions between said optical fiber connectors (14, 18) and said optical device (10). An optical device module according to Claim 1, wherein said second resin (50) is a silicon resin. An optical device module according to Claim 1, wherein said second resin (50) is an urethan resin. An optical device module according to Claim 1, wherein said first resin is an epoxy resin. An optical device module according to Claim 1, wherein said first resin is an urethan resin. An optical device module according to Claim 1, wherein said optical device (10) is a waveguide substrate with an optical waveguide (12) formed on the surface thereof. An optical device module according to Claim 1, wherein said first and second fiber connectors (14, 18) are coupled to said optical device (10) with an adhesive (42). A method of manufacturing an optical device module (100, 200, 400) comprising a module body (44) including an optical device (10) having first and second ends, a first fiber connector (14) holding a first optical fiber (16), coupled to the first end of said optical device (10), and a second fiber connector (18) holding a second optical fiber (20), coupled to the second end of said optical device (10); an enclosure body (54) of a first resin and integrally molded so as to enclose the whole of said module body (44); and a second resin (50) in the form of a gel interposed between said enclosure body (54) and said module body (44), said method of manufacturing the optical device module comprising: a step of applying said second resin (50) in the form of a gel onto said module body (44); a step of placing said module body (44) into a mold (52) of a molding device; a step of supporting said module body (44) so that at least said first and second fiber connectors (14, 18) and coupled portions between said fiber connectors and said optical device (10) are spaced apart from the inner wall surface of said mold (52); and a step of injecting said melting first resin into said mold (52) in which said module body (44) is placed and curing said first resin to form said enclosure body (54). A method of manufacturing an optical device module according to Claim 9, wherein said module body (44) is supported by holding said first and second optical fibers (16, 20) with support devices (46, 48) so that said module body is suspended, like a bridge, between said support devices. A method of manufacturing an optical device module according to Claim 9, wherein said module body is supported by setting said optical device of said module body on an upper end surface of a support rod (62) projecting upwards from a bottom surface of said mold (52). A method of manufacturing an optical device module according to Claim 9, wherein said second resin (50) is applied onto the peripheries of said first and second fiber connectors (14, 18) and the peripheries of coupled portions between said optical fiber connectors and said optical device (10). A method of manufacturing an optical device module according to Claim 9, wherein said second resin (50) is a silicon resin. A method of manufacturing an optical device module according to Claim 9, wherein said second resin (50) is an urethan resin. A method of manufacturing an optical device module according to Claim 9, wherein said first resin is an epoxy resin. A method of manufacturing an optical device module according to Claim 9, wherein said first resin is an urethan resin. A method of manufacturing an optical device module according to Claim 15, wherein said enclosure body (54) is made of said first resin in accordance with the transfer molding. A method of manufacturing an optical device module according to Claim 9, wherein said optical device (10) is a waveguide substrate with an optical waveguide (12) formed on the surface thereof. A method of manufacturing an optical device module according to Claim 9, wherein said first and second fiber connectors (16, 18) are coupled to said optical device (10) with an adhesive (42).

Inventors: HIRAI SHIGERU, ISHIKAWA SHINJI, SAITO MASAHIDE, SEMURA SHIGERU, YUI DAI, HIRAI,SHIGERU, ISHIKAWA,SHINJI, SAITO,MASAHIDE, SEMURA,SHIGERU, YUI,DAI, HIRAI,SHIGERU, C/O YOKOHAMA WORKS OF SUMITOMO, ISHIKAWA,SHINJI, C/O YOKOHAMA WORKS OF SUMITOMO, SAITO,MASAHIDE, C/O YOKOHAMA WORKS OF SUMITOMO, SEMURA,SHIGERU , C/O YOKOHAMA WORKS OF SUMITOMO, YUI,DAI , C/O YOKOHAMA WORKS OF SUMITOMO
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES, LTD.
Application year: 1994
Main classification: G02B6
IPC codes: G02B6